This invention relates to the manufacture of electrical contacts and more particularly to the manufacture of electrical contacts having precious metal contacting areas.
Even more particularly this invention relates to manufacturing electrical contacts to be positioned within an electrically insulative housing.
Contacts of the type described above are extensively used in the electronics industry to perform a variety of functions such as electrically connecting a printed circuit board to a plurality of corresponding circuits. In this particular arrangement, a single circuit board is positioned in an insulative housing. In doing so, the conducting areas on the board mate with corresponding contacting areas on the electrical contacts also positioned in the housing. Accordingly, the respective tail portions of each contact have joined thereto a lead from an externally located circuit. Such a lead is secured to the tail by utilizing well established techniques such as wire-wrapping or welding.
Previously known contacts having precious metal contacting areas have been manufactured utilizing methods and apparatus which position the precious metal, usually in the form of a gold or silver composition wire, upon the designed area on the contact and thereafter subject this area to either a cold or hot forming operation. Welding has been successively used to secure the precious metal to the contact but this method has usually required feeding the precious metal in the form of a wire vertically downward to the horizontally positioned flat surface of the contact. When contact is achieved, electrical current is applied and the weld occurs. Such a method is disclosed in U.S. Pat. No. 3,114,828 which is assigned to the same assignee as is the present invention. While both this and similar methods successfully produced a contact with precious metal contacting areas it can readily be seen that highly accurate control measures are required to control the amount of precious metal wire used during the welding sequence. On some occasions, excessive precious metal was wasted as a result of minor fluctuations in either the rate of feed of the wire or in the current densities applied. In those operations not utilizing welding as the attaching medium, the problems on several occasions have centered about inadequately achieved bonds between the contact surfaces and the precious metal. This particular problem is further amplified with repeated insertions of the printed circuit board into the connector housing.